The entire disclosure of Japanese Patent Application Nos. 8-331848, 8-331856, 9-093479, 9-168273, 9-258857 including specifications, claims, drawings and summaries is incorporated herein by reference in their entirety.
1. Field of the Invention
The present invention relates to a vibration detecting device for detecting vibration in a camera or an image pickup device for a video movie or the like, and a vibration reduction device for compensating the vibration. The invention also relates to a micro signal processing circuit which can be used in a vibration detecting circuit.
2. Related Background Art
For example, as a prior-art vibration detecting device known is a device which detects acceleration or angular velocity occurring in an apparatus by using an acceleration sensor, an angular velocity sensor or the like. In general, because the acceleration sensor or the angular velocity sensor itself outputs only a slight voltage in relation to a given vibration, an appropriate amplifier is provided outside the sensor for emitting a necessary voltage.
However, the vibration detecting sensor, especially a vibration sensing gyroscope of piezoelectric type generally used in a camera or the like outputs a remarkably unstable output for several tens to hundreds of milliseconds immediately after power turns on, and generates a low-frequency output drift even after the power turns on. Also, a voltage under the state in which no vibration is given (hereinafter, referred to as a stationary output voltage) is not always constant, and remarkably much varied with variation among vibration sensing gyroscopes or change in operational environment, especially with operation temperature. Such variation in output when power turns on is considerably large as compared with a level of an output signal for the vibration to be originally detected in accordance with the acceleration or the angular velocity, and in some case excessively large.
As a vibration detecting device in which an influence of the variation in output when power turns on is minimized, for example, a vibration detecting circuit disclosed in a publication of Japanese Patent Application Laid-Open No. 7-218953 is heretofore known. The vibration detecting circuit is constituted of an angular velocity sensor, a high pass filter for cutting an output of a tolerably low frequency relative to a frequency of a vibration to be detected from an output of the angular velocity sensor and an amplifying portion for amplifying a signal passed through the high pass filter.
FIG. 20 is a circuit diagram showing a vibration detecting circuit in the prior-art vibration detecting device. A vibration sensing gyroscope 1 detects an angular velocity caused by vibration in the device with a piezoelectric element. A circuit 2 is a three-dimensional low pass filter circuit for removing high-frequency components from an output of the vibration sensing gyroscope 1. In a circuit 3, a capacitor C4 and a resistor R4 constitute a high pass filter for removing low-frequency components which are not caused by the vibration, and an operational amplifier OP2 and resistors R6 and R7 constitute an amplifying circuit which amplifies an output signal of the circuit 2 in a non-inverting manner. The cut-off frequency which is a low frequency to be determined by the capacitor C4 and the resistor R4, needs to be sufficiently low relative to the frequency of the vibration to be detected, so that the cut-off frequency has no influence on the vibration which occurs in the apparatus. For the purpose, a numeric value of the cut-off frequency is, for example, set to about 0.1 Hz.
A switch SW1 is an analog switch which shifts the cut-off frequency to a high frequency when it is on and which is maintained on for a predetermined time after power is turned on so as to minimize an influence exerted on an output signal Vout by the variation in output when the power supply to the vibration sensing gyroscope 1 is started. When the switch SW1 is turned off, the low frequency of the cut-off frequency is determined by the capacitor C4 and the resistor R4. A power circuit 4 supplies a stable power to the vibration sensing gyroscope 1 and the circuits 2 and 3. In one chip computer (hereinafter, referred to as the MCU) 5, the output signal Vout from the circuit 3 is digitized by a built-in A/D converter 5a, the vibration occurring in the apparatus is detected, and also an operation of the power circuit 4 is controlled in accordance with a control signal PC of a control signal generator 5d. Further, in the MCU 5 the turning on/off of the analog switch SW1 is controlled in accordance with an operation signal SSW of an operation signal generator 5b. 
Also, in each of vibration detecting devices disclosed in publications of Japanese Patent Application Laid-Open Nos. 7-253604 and 8-82820, an output of a vibration sensing gyroscope and a reference voltage are differentially amplified by a differential amplifying portion, and a vibration occurring in the apparatus is detected from the output. An influence of an output drift of the vibration sensing gyroscope when power turns on and an influence of variations in stationary output voltage among individual vibration sensing gyroscopes are eliminated by controlling the output differentiated/amplified by changing the reference voltage within a dynamic range of the output.
However, the prior-art vibration detecting device has a first problem with the dynamic range of the vibration to be detected and a detecting resolution.
For example, when an angular velocity of a vibration is detected in a camera which uses a silver salt (or silver halide) film and has a function of reducing the vibration, at the time of usually shooting, a stationary object, a maximum value of the vibration angular velocity is approximately 20xc2x0 to 30xc2x0 per second though it varies depending on the individual users. On the other hand, when the camera pans, flows or picks up an object moving at a high speed, a very large angular velocity occurs as compared with in the case of shooting the stationary object. For example, the angular velocity exceeding 50xc2x0 per second occurs. When considering even the angular velocity which may occur at the time of shooting the object other than the stationary object, the dynamic range of the angular velocity up to 50xc2x0 per second or more needs to be secured.
In the camera having the vibration reducing function and using the silver salt film, a video movie or the like, as shown in FIG. 20, the detected output signal Vout is quantized to a digital value by using the A/D converter 5a, and the vibration reduction is usually performed based on the quantized vibration signal. In this case, since a quantization unit of the A/D converter 5a is finite, the resolution per bit of quantization needs to be increased by setting large an amplification factor for amplifying the output of the vibration sensing gyroscope 1. For the purpose, to enhance a ratio (S/N) of the signal to be detected with a noise included in the output of the operational amplifier OP2, a gain of the amplifying circuit constituted of the operational amplifier OP2, the resistors R6 and R7 and the like needs to be set large. However, since the output range of the operational amplifier OP2 is limited, the dynamic range of the angular velocity that can be detected is decreased when the resolution per bit of quantization is enhanced. In this manner, when priority is given to the dynamic range of the vibration to be detected, the resolution per bit of quantization or the ratio S/N is deteriorated. On the other hand, when priority is given to the resolution per bit of quantization or S/N, the dynamic range of vibration which can be detected is disadvantageously narrowed.
Secondly, a problem is caused by a time constant of the high pass filter.
The cut-off frequency of the high pass filter constituting the vibration detecting device has to be set sufficiently low relative to the frequency bandwidth of the vibration to be detected. For example, when the camera using the silver salt film or the video movie is used, the dominant frequency bandwidth of the vibration is said to be about 1 Hz to 15 Hz. In this case, the cut-off frequency of the high pass filter which is determined by the capacitor C4 and the resistor R4 should be suppressed low, for example, around 0.1 Hz. Therefore, the time constant determined by the capacitor C4 and the resistor R4 becomes very large. As a result, it takes so much time as cannot be ignored until the output signal Vout is stabilized. In the vibration detecting device described in the publication of Japanese Patent Application Laid-Open No. 7-218953, the output of the vibration sensing gyroscope 1 behaves unstably when power turns on. For this, in the vibration detecting device, to secure the stability of the output signal Vout, when power is turned on, the analog switch SW1 shown in FIG. 20 is turned on for a predetermined period of time.
FIG. 21 is a timing chart when power turns on in the prior-art vibration detecting device.
At a time t0, by setting high the control signal PC as shown in FIG. 21, the power supply circuit 4 is operated, thereby supplying power to the vibration sensing gyroscope 1 and the circuits 2 and 3 via a power line Vdd. During a period of time from t1 to t2, by setting high the operation signal SSW, the influence of a large variation in output when power turns on in the vibration sensing gyroscope 1 is suppressed by the turning-on of the analog switch SW1. A signal detected by the vibration sensing gyroscope 1 after setting low the operation signal SSW at a time t2 is amplified by the amplifier constituted of the operational amplifying portion OP2 and the like, and a signal which substantially represents the vibration applied to the apparatus is outputted as the output signal Vout.
For example, when the vibration shown in FIG. 21 (the angular velocity vibration in a form of sinusoidal wave) is applied to the apparatus and at the time t2 the analog switch SW1 is turned off, then the output signal Vout starts to be outputted with its angular velocity at the time t2 being substantially 0V. Namely, the output signal Vout does not have a wave form in which Vout assumes zero (0V) when the angular velocity is zero, but, as shown in FIG. 21, a waveform which is shifted upward. In other words, a signal which is obtained by offsetting the vibration angular velocity applied to the vibration sensing gyroscope 1 by a certain error is outputted. The error (hereinafter, referred to as the offset error) does not have a constant value, and varies with an elapse of time. The time constant is determined by the capacitor C4 and the resistor R4, and the center of the amplitude of the output signal Vout approaches 0V. For this, when the apparatus is used with the vibration applied thereto, due to the time constant determined by the capacitor C4 and the resistor R4, a vibration detecting error occurs in the output signal Vout. As a result, to detect a precise angular velocity, it needs to take time from when power turns on until the offset error is reduced to a tolerable quantity. The time elapsed until the offset error can be ignored was intolerably large in a field to which the vibration detecting device is applied, especially in the camera using the silver salt film.
In the publication of Japanese Patent Application Laid-Open No. 7-218953, to reduce the offset error, substantially at the center of the amplitude of the output signal Vout, the analog switch SW1 is again turned on from time t3 to t4, thereby reducing the amplitude to a vicinity of 0V (zero volt). However, since this countermeasure for reducing the offset error is not effective for all the amplitude waveforms, and the offset error surely occurs.
Also, in the vibration detecting device proposed by the publications of Japanese Patent Application Laid-Open Nos. 7-253604 and 8-82820, since the reference voltage and the output of the vibration sensing gyroscope are differentially amplified, the change in reference voltage is amplified by the differential amplifier. The amplification factor of the differential amplifier is usually set in such a manner that a micro output of the vibration sensing gyroscope is amplified to provide a necessary vibration detecting resolution. Therefore, a micro change in reference voltage is amplified at the amplification factor and outputted. Also, in the vibration detecting device proposed in the publication of Japanese Patent Application Laid-Open No. 7-253604, to suppress the influence of the output drift of the vibration sensing gyroscope when power turns on and the influence of the variations in stationary output voltage among the vibration sensing gyroscopes, the reference voltage is changed to adjust and the differentially amplified output within its output dynamic range. As a result, the resolution for changing the reference voltage as a nicked quantity in changing the reference voltage needs to be high to some degree. The circuit related to the reference voltage is difficult to design, which increases the cost.
Another prior-art vibration reduction device is disclosed, for example, in a publication of Japanese Patent Application Laid-Open No. 2-183217. In the vibration reduction device, a vibration which occurs in a camera or a video camera is detected by an angular velocity sensor or another sensor, and a vibration reduction lens is moved in a direction reverse to the direction of the vibration detected by the sensor to compensate the vibration.
An example of a camera provided with a vibration reduction device is described with reference to FIG. 26.
FIG. 26 is a block diagram showing a general constitution of a camera provided with a vibration reduction device.
A camera body 101 is provided with a battery 103 for supplying power to the camera body 101 and a lens barrel 102, a camera body DC/DC converter 104, a camera body CPU 105 for executing a main control of the camera body, a main switch 112 for turning on a camera power, a half-stroke switch 111 which turns on in a first stroke (half-pressed condition) of a release button, a full-stroke switch 110 which turns on in a second stroke (full-pressed condition) of the release button, an operation switch 100 and a power-supply control switch 130 as a semiconductor switch and the like.
The lens barrel 102 is provided with a lens barrel CPU 119 for executing a main control of the lens barrel, a lens barrel DC/DC converter 120, two-bit selection switches 131 and 132 for selecting a vibration reduction control mode, vibration detectors 113 and 114 for detecting the vibration and emitting an output signal in accordance with a quantity of the vibration, a first lens group 125, a second lens group 126, a third lens group (hereinafter, the vibration reduction lens) 127 for being driven in a direction vertical or substantially vertical to an optical axis to compensate the vibration, a stop blade 128, motors 123 and 124 for driving the vibration reduction lens 127, control circuits 121 and 122 for driving and controlling the motors 123 and 124, respectively, and the like.
In the prior-art vibration reduction device, the vibration of a image surface formed on a plane is decomposed into components of mutually orthogonal X and Y axes, and a vibration reduction mechanism portion is operated along respective axial directions to nullify the direction of the vibration. For this, since the two motors 123 and 124 are necessary as drive sources for driving the vibration reduction lens 127 along two axes, there are provided two vibration detectors 113 and 114 and two control circuits 121 and 122. The vibration detector 113 is now described.
FIG. 27 is a block diagram showing an example of the vibration detecting circuit in the prior-art vibration reduction device.
The vibration detector 113 shown in FIG. 26 is, as shown in FIG. 27, provided with a vibration detecting circuit constituted of an angular velocity sensor (vibration sensing gyroscope 201), a low pass filter (hereinafter, referred to as the LPF) 202 connected to the angular velocity sensor 201, a high pass filter (referred to as the HPF) 203 connected to the LPF 202, an amplifier (AMP) 204 connected to the HPF 203 and an A/D converter 205 connected to the AMP 204.
The angular velocity sensor 201 detects a vibrating condition as the angular velocity, and outputs an output signal based on the angular velocity. The output signal is transmitted to the next LPF 202.
The LPF 202 is a filter which blocks a high-frequency component of the output signal of the angular velocity sensor 201. The signal having its high-frequency component cut off is transmitted to the next HPF 203.
The HPF 203 is a filter for blocking a low-frequency component of the signal whose high-frequency component has been blocked by the LPF 202. The signal having its low-frequency component cut off is transmitted to the next amplifier 204.
The amplifier 204 amplifies the signal whose low-frequency component has been blocked by the HPF 203, and the amplified signal is transmitted to the next A/D converter 205.
The A/D converter 205 converts the analog signal whose low-frequency component is blocked by the HPF 203 into a digital signal and outputs the digital signal.
In the aforementioned sequence of analog signal processing circuit, the signal indicative of the frequency of the vibration in the camera or the like is processed. Therefore, the frequency of the processed signal ranges from several herz to decades of herz.
The analog-processed data has a dimension of angular velocity. Therefore, when based on the data the vibration reduction lens 127 is operated, a reference value of the angular velocity (detecting device output reference value) xcfx890 (hereinafter, referred to as omega zero) needs to be calculated. By calculating the omega zero, at the time of panning at a constant speed, its condition different from the vibrating condition can be reflected in the compensating operation. The vibration reduction lens 127 is operated in accordance with a compensation quantity which is proportional to a difference between the omega zero and the processed data of the detected angular velocity. The omega zero is calculated from an equation: xcfx890=(1/T)xcexa3xcfx89(t). This is obtained by averaging the sum of angular velocities xcfx89(t) at respective times from 0 to T with the time T. The ideal angular velocity data used in the equation is the data which is detected when the output of the angular velocity sensor 201 is stabilized and the camera is determined not to be in the vibrating condition. Also, the longer the time (detecting time) T for averaging is, the more stable the data is.
The camera body 101 and the lens barrel 102 are, as shown in FIG. 26, electrically interconnected by electric contacts 115, 116, 117 and 118. The electric contact 115 is a contact for supplying power from the battery 103 via the power-supply control switch 130 to the lens barrel 102. The electric contact 116 electrically supplies the output of the camera body DC/DC converter 104 to the lens barrel 102. The electric contact 117 is for communication between the camera body CPU 105 and the lens barrel CPU 119. The electric contact 118 connects a ground (GND) line to a cathode terminal of the battery 103.
An operation of the prior-art vibration reduction device is now described.
When the main switch 112 and then the half-stroke switch 111 are turned on, an L-level signal is transmitted to associated terminals of the camera body CPU 105. Subsequently, when the full-stroke switch 110 is turned on, the L-level signal is transmitted to an associated terminal of the camera body CPU 105. When the half-stroke switch 111 is turned on, the camera body CPU 105 activates and controls the camera body DC/DC converter 104, thereby supplying power via the electric contact 116 to the lens barrel CPU 119.
The lens barrel CPU 119 transmits a power-supply request signal via the electric contact 117 to the camera body CPU 105. The camera body CPU 105 turns on the power-supply control switch 130, and the battery 103 supplies power via the electric contact 115 to the lens barrel DC/DC converter 120. Also, the lens barrel CPU 119 receives the power supply from the electric contact 116 to activate the lens barrel DC/DC converter 120. The lens barrel DC/DC converter 120 supplies power to the control circuits 121 and 122 and the motors 123 and 124.
When the setting switch 132 is turned on, an L-level signal is transmitted to a terminal D1 of the lens barrel CPU 119. When the setting switch 131 is turned on, the L-level signal is transmitted to a terminal D2 of the lens barrel CPU 119. On the other hand, when the setting switch 132 is turned off, the terminal D1 of the lens barrel CPU 119 has an H level, while when the setting switch 131 is turned off, the terminal D2 of the lens barrel CPU 119 has an H level.
When the terminal D1 has an L level and the terminal D2 has an H level, for the vibration reduction control mode a mode in which compensating operation is performed only during exposure is selected. When the terminal D1 has an H level and the terminal D2 has an L level, for the vibration reduction control mode a mode in which the compensating operation is performed during and except the exposure time period is selected. When the terminal D1 has an H level and the terminal D2 has an H level, for the vibration reduction control mode a mode in which no vibration reduction operation is performed is selected.
The vibration detectors 113 and 114 analog-process the output signal indicative of the quantity of detected vibration, and transmits the processed signal to the lens barrel CPU 119. When the mode for performing the compensating operation during and except the exposure time period is selected as the vibration reduction control mode and the half-stroke switch 111 is turned on, then the lens barrel CPU 119 calculates a drive quantity of the vibration reduction lens 127 based on the analog-processed data.
The vibration detectors 113 and 114 output the output signal indicative of the quantity of detected vibration from when power is supplied. The lens barrel CPU 119 starts detecting omega zero from when the vibration detectors 113 and 114 output the output signal. The time necessary for detecting omega zero is about two seconds when there is a sufficient detecting time. However, when shooting immediately after power turns on, even two seconds cannot be secured. In this case, omega zero is detected as long as possible. When a user shoots, the lens barrel CPU 119 calculates a compensation quantity based on the data of omega zero which have been detected just before the shooting. Based on the compensation quantity, the motors 123 and 124 are feedback-controlled.
Based on the computed compensation quantity, the lens barrel CPU 119 instructs the control circuits 121 and 122 to drive the motors 123 and 124. The rotary movement of the motors 123 and 124 is converted to a linear movement, thereby driving the vibration reduction lens 127.
Additionally, when the mode for performing the compensating operation only during the exposure is selected as the vibration reduction control mode and the full-stroke switch 110 is turned on, then the vibration reduction lens 127 is driven only during the exposure.
FIG. 28 is a circuit diagram showing an example of the vibration detecting circuit in the prior-art vibration reduction device.
The vibration detecting circuit shown in FIG. 28 is provided with a first step of a three-dimensional LPF (DC-coupled) 10 constituted of capacitors C111, C112 and C113, resistors R111, R112 and R113 and an operational amplifier OP111, a second step of a first-dimensional HPF (AC-coupled) 20 constituted of a capacitor C121 and a resistor R121, and a third step of a 100-times amplifier 30 constituted of a capacitor C131, a resistor R131 and an operational amplifier OP131.
In FIG. 28, in the first step of the LPF 10, an input angular velocity signal has its high-frequency component cut off, and a signal phase in a pass band is delayed at the same time. Since the phase delay causes an error in the vibration reduction control, the phase delay is desirably close to zero. For this, the cut-off frequency of the LPF 10 is set to a degree to which the phase delay can be ignored, for example, to about 300 Hz. The signal whose high-frequency component has been cut off is transmitted to the second step of HPF 20.
FIG. 29 is a block diagram showing another example of the vibration detecting circuit in the prior-art vibration reduction device.
An output signal indicative of a vibration quantity outputted from an angular velocity sensor 201 originally includes a low-frequency signal (a drift component over a long period of time), and its minimum detecting amplitude is small. If the output signal outputted from the angular velocity sensor 201 is multiplied by the gain in the amplifier 204 without any signal processing, a component of an output signal from the amplifier 204 is saturated by a low-frequency component and cannot be used. To block the low-frequency component, as shown in FIG. 28, the HPF 20 having a cut-off frequency of, for example, about 0.6 Hz is used. In this manner, in the circuit constitution shown in FIG. 28, the signal whose low-frequency and high-frequency components have been cut off is amplified in the third step of the amplifier 30. The amplifier 30 constitutes a non-inverting amplifying circuit and multiplies a 101-times gain.
In the processing of the output signal outputted from the angular velocity sensor 201 in the circuit constitution shown in FIG. 28, when an excessively large input signal is applied to the amplifier 30, the signal multiplied by the gain in the amplifier 30 is outputted from the amplifier 30.
FIG. 30 schematically shows a condition in which the output voltage of the angular velocity sensor exceeds its dynamic range.
The dynamic range of the output voltage indicative of the vibration quantity emitted from the angular velocity sensor 201 is limited by the power source voltage and the circuit constitution of the output step. Therefore, as shown by an arrow P in FIG. 30, in some case at the time of panning or other manipulation of the camera, the output voltage from the amplifier 30 exceeds its dynamic range (shown by a broken line), and is saturated. If the saturated condition is let as it is, the output voltage approaches a reference point without limitation in a manner which accords with the time constant of the circuit because of the characteristics of the HPF (AC-coupled) 20. However, since the time constant of the HPF 20 is of the order of several seconds, a considerable time is necessary until the output voltage from the amplifier 30 reaches the reference point. Immediately after an excessively large vibration occurs, a usual vibration reduction cannot be performed. To avoid this problem, in the vibration detecting circuit shown in FIG. 28, the time constant of the HPF 20 is shortened by an analog switch SW141.
FIG. 31 diagrammatically shows a condition in which the output voltage of the angular velocity sensor is returned to within the dynamic range.
When the output voltage outputted from the angular velocity sensor 201 is saturated and the analog switch SW141 is turned on, then as shown in FIG. 31, the output voltage from the amplifier 30 can be returned to the reference point in a short time T (about 20 ms).
FIG. 32 is a circuit diagram showing another example of the vibration detecting circuit in the prior-art vibration reduction device.
The vibration detecting circuit shown in FIG. 32 is provided with a first-step inverting amplifier 60 which is constituted of a capacitor C261, a resistor R261 and an operational amplifier OP261, also serves as an LPF and which cuts a direct current, a second step of a reverse amplifier 70 which is constituted of a capacitor C271, resistors R271, R272 and R273 and an operational amplifier OP271 and also serves as an LPF, an HPF 50 which is constituted of a capacitor C251 and a resistor R251 and blocks a direct current, and the like.
In the vibration detecting circuit shown in FIG. 32, since a portion interconnected with the resistor which is multiplied by the gain of the input of the operational amplifier OP261 is insulated by the capacitor C251 in a direct current manner, an offset adjustment is unnecessary. In this circuit arrangement, the offset output of the operational amplifier OP261 in the first step is not multiplied by the gain of the first-step inverting amplifier 60. When the gain of the first step is sufficiently large and the gain of the next step is lowered, then an output of offset voltage is naturally small. The time constant of the HPF 50 is determined by the resistor R251 and the capacitor C251, and the resistor R251 has a function of setting the gain together with the resistor R261.
In the prior-art vibration detecting circuit shown in FIG. 28, when the input offset voltage has an influence on the operational amplifier OP131 of the final step between the HPF 20 and the amplifier 30, the offset voltage is multiplied by the gain in the operational amplifier OP131 and outputted. Also, when the input bias current has an influence on the operational amplifier OP131 in the final step, by turning on and off the analog switch SW141, the balance in bias current between a plus terminal and a minus terminal of the operational amplifier OP131 is changed. The change in balance of the bias current causes a change in voltage, which is outputted as an output of the operational amplifier OP131. To prevent the output from being saturated, in the vibration detecting circuit shown in FIG. 28, the offset adjustment is made by a variable resistor R144, but the cost of the offset adjustment cannot be ignored.
Also, in the prior-art vibration detecting circuit shown in FIG. 32, when the gain of the inverting amplifier 70 associated with the offset is reduced, the gain needs to be increased in the inverting amplifier 60 of the first step. As a result, the capacity of the capacitor C251 for setting the time constant of the HPF 50 is accordingly increased. When the capacity of the capacitor C251 is increased and the output voltage is saturated, a converging time is lengthened when analog switches SW261 and SW281 are turned on.
FIG. 40 is a table showing voltages and corresponding angular velocities when a voltage difference against a stationary value at an elapsed time t is multiplied by the gain (100 times) when a step voltage of E=5V is transmitted to the HPF 50 at a time 0.
For example, to suppress a variation voltage in amplifier output to 168 mV (1.68 deg/sec) or less, a time during which the analog switch SW81 is turned on needs to be 340 ms at maximum.
The aforementioned vibration detecting circuit shown in FIG. 29 is constituted of the angular velocity sensor 201 for detecting the vibrating condition as an angular velocity and emitting an output signal in accordance with the angular velocity, the AMP 204 for receiving an output signal of the angular velocity sensor 201 and amplifying the output signal, the LPF 202 for receiving an output signal of the AMP 204 and blocking a high-frequency component in the output signal and the A/D converter 205 for receiving an output signal of the LPF 202, converting the output signal from an analog signal to a digital signal and emitting the converted signal.
Since the vibration detecting circuit shown in FIG. 29 is not provided with an HPF, a low-frequency component can be processed as information. However, because no HPF is disposed in the vibration detecting circuit, an error caused by a DC offset component of the circuit itself is amplified. Also, the output signal indicative of the vibration quantity from the angular velocity sensor 201 includes a low-frequency signal (drift component over a long period of time). As shown in FIG. 29, if the output signal of the angular velocity sensor 201 is multiplied by the gain as it is in the amplifier 204, the output signal of the amplifier 204 is saturated by the low-frequency component and cannot be used. For this reason, the vibration detecting circuit is difficult to use for detecting the vibration.
In a camera electronic circuit, since a battery constitutes a power supply, a power voltage in a processing circuit or the like usually tends to be reduced to save power. Generally, in a commercial operational amplifier, an input common-mode voltage range is narrowed when the power voltage is low. Also, in some range of input voltage, a transistor inside the operational amplifier does not operate. When the vibration detecting circuit shown in FIG. 29 is constituted of the commercial operational amplifier, the range of the input voltage is predetermined by its standard. Therefore, the vibration detecting circuit needs to be constituted in such a manner that processing can be performed in the predetermined standard range.
Usually in the operational amplifier, to increase its stability and enlarge its band by applying a negative feedback, an output signal is fed back to an inverting (xe2x88x92) input terminal. In this case, since an imaginary short is established, the inverting input terminal and a non-inverting (+) input terminal are operated to keep the same electric potential. In the vibration detecting circuit shown in FIG. 29, when the operational amplifier is used in a non-inverting input format, the input signal as well as the input voltage are changed on the inverting input terminal and the non-inverting input terminal. If the input signal to the operational amplifier is dispersed, there is a possibility that a signal exceeding its standard range is inputted, even when the operational amplifier is intended to operate within the standard range. Especially, the angular velocity sensor for detecting the vibration (piezoelectric vibration sensing gyroscope) 201 has a large dispersion in output voltage relative to the reference voltage. For this reason, when an output voltage exceeding the input voltage range of the operational amplifier is applied, in the operational amplifier having some performance the input common-mode voltage range is probably exceeded. As a result, the selection of the operational amplifier is limited, thereby increasing the cost.
An object of an aspect of the invention is to provide a vibration detecting circuit which can firstly ensure a dynamic range while enhancing a detecting resolution as high as possible, secondly reduce an offset error caused by a time constant of a high pass filter and which can thirdly facilitate a circuit design of a reference voltage and reduce its cost.
To attain the object, a first mode of the invention provides a vibration detecting device which includes a vibration detector for detecting a vibration and outputting a vibration detecting signal, a calculator for performing a predetermined operation based on the vibration detecting signal and a controller for determining whether or not an operation output signal of the calculator exceeds a predetermined range. The controller is provided with an operation signal generator for generating an operation signal when the operation output signal exceeds the predetermined range. The calculator is provided with an initializing portion for returning the operation output signal back to the predetermined range based on the operation signal.
According to a second mode of the invention, in the vibration detecting device of the first mode, the controller is provided with a compensating portion for compensating the operation output signal based on the operation output signal before and after being returned by the calculator.
According to a third mode of the invention, the vibration detecting device of the first or second mode is further provided with a high pass filter for removing a low-frequency component from the vibration detecting signal. The initializing portion is provided with an amplifying portion for amplifying an output of the high pass filter.
According to a fourth mode of the invention, the vibration detecting device of the first or second mode includes a low pass filter for removing a high-frequency component from the vibration detecting signal and a high pass filter for removing a low-frequency component from an output of the low pass filter. The initializing portion is provided with an amplifying portion for amplifying an output of the high pass filter.
A fifth mode of the invention provides a vibration detecting device which includes a vibration detector for detecting a vibration and outputting a vibration detecting signal, an output signal generator for generating an output signal, a calculator for performing a predetermined operation based on the vibration detecting signal and the output signal to generate an operation output signal, a controller for controlling the output signal generator based on the operation output signal and an operation signal generator for generating an operation signal for controlling the output signal generator. The output signal generator is provided with an output signal level variable portion which can vary a level of the output signal based on the operation signal.
According to a sixth mode of the invention, in the vibration detecting device of the fifth mode, the controller determines whether or not the operation output signal exceeds a predetermined range and, when the operation output signal exceeds the predetermined range, makes the operation signal generator generate the operation signal to adjust in such a manner that the operation output signal is in the predetermined range.
According to a seventh mode of the invention, in the vibration detecting device of the sixth mode, the controller is provided with a compensating portion for compensating the operation output signal based on the operation output signal before and after being adjusted.
According to an eighth mode of the invention, in the vibration detecting device of the fifth mode, the controller determines whether or not the operation output signal exceeds a predetermined range, the operation signal generator generates the operation signal when the operation output signal exceeds the predetermined range, the output signal level variable portion varies the level of the output signal by a predetermined level based on the operation signal, and the controller adjusts the operation output signal in the predetermined range.
According to a ninth mode of the invention, in the vibration detecting device of the eighth mode, the controller is provided with a compensating portion for compensating the operation output signal based on the operation output signal before and after being adjusted and the predetermined level.
According to a tenth mode of the invention, in the vibration detecting device of the eighth mode, the controller is provided with a compensating portion for compensating the operation output signal based on the operation output signal before and after being adjusted.
According to an eleventh mode of the invention, in the vibration detecting device of the fifth mode, the controller determines whether or not the operation output signal is deviated from a predetermined reference level, the operation signal generator generates the operation signal when the operation output signal is deviated from the predetermined reference level, and the controller adjusts the operation output signal to the predetermined reference level or its vicinity.
According to a twelfth mode of the invention, the vibration detecting device of the fifth mode is provided with a power supply portion for supplying a power at least to the vibration detector. The controller makes the operation signal generator generate the operation signal when the power supply portion starts supplying the power to the vibration detector, and adjusts the operation output signal of the calculator to a predetermined reference level or its vicinity.
A thirteenth mode of the invention provides a vibration detecting device which includes a vibration detector for detecting a vibration and emitting a vibration detecting signal, an output signal generator for generating at least first and second output signals, a calculator for performing a predetermined operation based on the first output signal and/or the second output signal and the vibration detecting signal to generate an operation output signal, a controller for controlling the output signal generator based on the operation output signal and an operation signal generator for generating an operation signal for controlling the output signal generator. The output signal generator is provided with an output signal level variable portion which varies a level of the first output signal and/or the second output signal based on the operation signal.
According to a fourteenth mode of the invention, in the vibration detecting device of the thirteenth mode, the output signal generator is provided with at least first and second output signal generators, the operation signal generator generates first and second operation signals for controlling the first and second output signal generators, and the output signal level variable portion is provided with a first output signal level variable portion which can vary a level of the first output signal based on the first operation signal and a second output signal level variable portion which can vary a level of the second output signal based on the second operation signal.
According to a fifteenth mode of the invention, in the vibration detecting device of the thirteenth or fourteenth mode, the controller determines whether or not the operation output signal exceeds a predetermined range, and when the operation output signal exceeds the predetermined range, makes the operation signal generator generate the operation signal so as to vary a level of the first output signal and/or the second output signal to adjust the operation output signal in the predetermined range.
According to a sixteenth mode of the invention, in the vibration detecting device of the thirteenth or fourteenth mode, the controller is provided with a compensating portion for compensating the operation output signal based on the operation output signal before and after being adjusted.
According to a seventeenth mode of the invention, in the vibration detecting device of the thirteenth or fourteenth mode, the controller determines whether or not the operation output signal exceeds a predetermined range, the operation signal generator generates the operation signal when the operation output signal exceeds the predetermined range, the output signal level variable portion varies the level of the first output signal and/or the second output signal based on the operation signal by a predetermined level, and the controller adjusts the operation output signal in the predetermined range.
According to an eighteenth mode of the invention, in the vibration detecting device of the seventeenth mode, the controller is provided with a compensating portion for compensating the operation output signal based on the operation output signal before or after being adjusted and the predetermined level.
According to a nineteenth mode of the invention, in the vibration detecting device of the seventeenth mode, the controller is provided with a compensating portion for compensating the operation output signal based on the operation output signal before and after being adjusted.
According to a twentieth mode of the invention, in the vibration detecting device of the thirteenth or fourteenth mode, the operation signal generator generates the operation signal at predetermined timing, and the controller adjusts the operation output signal to a predetermined reference level or its vicinity.
According to a twenty-first mode of the invention, the vibration detecting device of the thirteenth or fourteenth mode is provided with a power supply portion for supplying a power at least to the vibration detector. The predetermined timing is a timing corresponding to a time when the power supply portion starts supplying the power to the vibration detector.
According to a twenty-second mode of the invention, in the vibration detecting device of the twentieth or twenty-first mode, the controller coarsely adjusts the operation output signal to the predetermined reference level or its vicinity based on the first output signal, and finely adjusts the operation output signal to the predetermined reference level or its vicinity based on the second output signal.
According to a twenty-third mode of the invention, the vibration detecting device of either one of the fifth to twenty-second modes is provided with a low pass filter for removing a high-frequency component from the vibration detecting signal. The calculator is provided with an amplifying portion for amplifying an output of the low pass filter and an output signal of the output signal generator.
According to a twenty-fourth mode of the invention, in the vibration detecting device of either one of the fifth to twenty-third modes, the operation signal generator generates a digital signal, and the output signal generator is provided with a D/A converter for outputting an analog signal based on the digital signal.
According to a twenty-fifth mode of the invention, in the vibration detecting device of either one of the fifth to twenty-fourth modes, the calculator is provided with an adder for adding the output signal of the output signal generator and the vibration detecting signal.
According to a twenty-sixth mode of the invention, in the vibration detecting device of either one of the fifth to twenty-fourth modes, the calculator is provided with an adding amplifier performing an addition of the output signal of the output signal generator and the vibration detecting signal and amplifying the added signal.
According to a twenty-seventh mode of the invention, the vibration detecting device of either one of the fifth to twenty-fourth modes is provided with a low pass filter for removing a high-frequency component from the vibration detecting signal. The calculator is provided with an adding amplifier for performing an addition of an output signal of the low pass filter and the output signal of the output signal generator and amplifying the added signal.
According to a twenty-eighth mode of the invention, in the vibration detecting device of either one of the fifth to twenty-fourth modes, the calculator is provided with a subtracter for subtracting the output signal of the output signal generator and the vibration detecting signal.
According to a twenty-ninth mode of the invention, in the vibration detecting device of either one of the fifth to twenty-fourth modes, the calculator is provided with a subtracting amplifier for performing a subtraction of the output signal of the output signal generator and the vibration detecting signal and an amplification.
According to a thirtieth mode of the invention, the vibration detecting device of either one of the fifth to twenty-fourth modes is provided with a low pass filter for removing a high-frequency component from the vibration detecting signal. The calculator is provided with a subtracting amplifier for performing subtraction of an output signal of the low pass filter and the output signal of the output signal generator and an amplification.
An object of another aspect of the invention is to provide a vibration reduction device which can first minimize without making an offset adjustment an offset component multiplied by a gain and emitted at a final step of a processing circuit when a vibration detecting signal is processed in the processing circuit and which can secondly quickly converge an output voltage to an amplifying reference voltage before the output voltage is saturated.
To attain the object, a thirty-first mode of the invention provides a vibration reduction device which includes a vibration reduction optical system for compensating a vibration by driving at least a portion of a photographing optical system in a direction vertical to an optical axis, a drive portion for driving the vibration reduction optical system, a vibration detector for detecting the vibration and emitting an output voltage corresponding to a vibration quantity and a controller for driving and controlling the drive portion. The vibration reduction device is provided with a DC voltage generator for generating a DC voltage and a calculator for performing a predetermined operation based on the output voltage of the vibration detector and the DC voltage to emit an output signal. The controller is provided with an operation signal generator for generating an operation signal when the output signal is not in a predetermined range. The DC voltage generator generates the DC voltage based on the operation signal, and the calculator adjusts the output signal in the predetermined range based on the output voltage of the vibration detector and the DC voltage. According to the invention of the thirty-first mode, when the output signal of the calculator is not in the predetermined range, the controller makes the DC voltage generator generate the DC voltage, and the calculator performs the arithmetic operation based on the DC voltage and the output voltage of the vibration detector, so that the output voltage of the vibration detector is in the predetermined range. Therefore, the offset component can be minimized without making the offset adjustment, while the output voltage of the vibration detector can be quickly converged to the vicinity of the reference voltage.
According to a thirty-second mode of the invention, in the vibration reduction device of the thirty-first mode, the predetermined range does not exceed a dynamic range of the output signal of the calculator. According to the invention of the thirty-second mode, the predetermined range does not exceed the dynamic range. Therefore, when an excessively large vibration is transmitted to the vibration detector, the signal can be captured in the dynamic range before the output voltage exceeds the dynamic range, and the output signal can be quickly converged to the vicinity of the reference voltage.
According to a thirty-third mode of the invention, in the vibration reduction device of the thirty-first or thirty-second mode, the vibration detector, the calculator and the controller are DC-coupled. According to the invention of the thirty-third mode, since the vibration detector, the calculator and the controller are DC-coupled, the vibration detecting signal included in the low-frequency component can be effectively used.
According to a thirty-fourth mode of the invention, in the vibration reduction device of either one of the thirty-first to thirty-third modes, the DC voltage generator is provided with a DC voltage value variable portion for varying a DC voltage value based on the operation signal. According to the invention of the thirty-fourth mode, since the DC voltage generator is provided with the DC voltage value variable portion which can vary the DC voltage value, the output signal can be in a predetermined range based on the DC voltage which can be varied to an optional voltage value and the vibration detecting signal.
According to a thirty-fifth mode of the invention, in the vibration reduction device of the thirty-fourth mode, the controller is provided with a pulse width modulating portion for generating an operation signal, and the DC voltage value variable portion is provided with a switch for operating in accordance with the operation signal. According to the invention of the thirty-fifth mode, since the controller is provided with the pulse width modulating portion for generating the operation signal and the DC voltage value variable portion is provided with the switch for operating in accordance with the operation signal, the DC voltage generated by the DC voltage generator can be varied to an optional voltage value by the switch which operates in response to the operation signal.
According to a thirty-sixth mode of the invention, in the vibration reduction device of either one of the thirty-first to thirty-third modes, the controller is provided with a pulse width modulating portion for generating an operation signal, and the DC voltage generator is provided with a switching portion for operating based on the operation signal and switching an output voltage of a DC voltage source and a low pass filter for smoothing a switched rectangular wave. According to the invention of the thirty-sixth mode, the DC voltage generator is provided with the switching portion for operating based on the operation signal and switching the output voltage of the DC voltage source and the low pass filter for smoothing the switched rectangular wave, the DC voltage generated by the DC voltage generator is set to an effective voltage value and can be changed to a smoothed DC voltage.
According to a thirty-seventh mode of the invention, in the vibration reduction device of either one of the thirty-fourth to thirty-sixth modes, the operation signal generator generates the operation signal before the output signal exceeds the dynamic range, and the DC voltage value variable portion, the switching portion and the switch can vary the DC voltage value in accordance with a duty ratio between an ON time and an OFF time of the operation signal. According to the invention of the thirty-seventh mode, since the DC voltage value variable portion, the switching portion and the switch can vary the DC voltage value in accordance with the duty ratio between the ON time and the OFF time of the operation signal, the effective voltage value of the DC voltage generated by the DC voltage generator can be set to an optional voltage value.
An object of further aspect of the invention is to provide a micro signal processing circuit and a vibration detecting circuit which can process largely dispersed micro signals without being limited by an input common-mode voltage range of an amplifying portion and which have a little number of components and are advantage in mounting.
To attain this object, a thirty-eighth mode of the invention provides a micro signal processing circuit which includes a low pass filter portion having an inverting input terminal for receiving a micro signal and a non-inverting input terminal with a reference potential applied thereto for removing a high-frequency component from the micro signal and an amplifying portion to which an output signal of the low pass filter is inputted. The invention of the thirty-eighth mode includes the low pass filter portion having the inverting input terminal for receiving the micro signal and the non-inverting input terminal with the reference potential applied thereto for removing the high-frequency component from the micro signal and the amplifying portion to which the output signal of the low pass filter is inputted. Therefore, a formed circuit is not limited by the input common mode voltage range of the amplifying portion.
A thirty-ninth mode of the invention provides a micro signal processing circuit which includes an amplifying portion having an inverting input terminal for receiving a micro signal and a non-inverting input terminal with a reference potential applied thereto and a low pass filter portion for receiving an output signal of the amplifying portion and removing a high-frequency component from the micro signal. The invention of the thirty-ninth mode includes the amplifying portion having the inverting input terminal for receiving the micro signal and the non-inverting input terminal with the reference potential applied thereto and the low pass filter portion for receiving the output signal of the amplifying portion and removing the high-frequency component from the micro signal. Therefore, a formed circuit can be limited by the input common mode voltage range of the amplifying portion.
A fortieth mode of the invention provides a micro signal processing circuit which comprises an output signal generator for generating an output signal, a calculator having an inverting input terminal for receiving a micro signal and a non-inverting input terminal with a reference potential applied thereto for performing a predetermined operation based on the micro signal and the output signal of the output signal generator, a low pass filter portion for removing a high-frequency component from the output signal of the calculator, an amplifying portion for receiving an output signal of the low pass filter portion and an operation signal generator for generating an operation signal when an output signal of the amplifying portion is not in a predetermined range. Based on the micro signal and the output signal of the output signal generator, the output signal of the amplifying portion is adjusted in the predetermined range. According to the invention of the fortieth mode, the calculator has the inverting input terminal for receiving the micro signal and the non-inverting input terminal with the reference potential applied thereto to perform the predetermined operation based on the micro signal and the output signal of the output signal generator. The low pass filter portion removes the high-frequency component from the output signal of the calculator. The output signal of the low pass filter portion is transmitted to the amplifying portion. The operation signal generator generates the operation signal when the output signal of the amplifying portion is not in the predetermined range. Based on the micro signal and the output signal of the output signal generator, the output signal of the amplifying portion is adjusted in the predetermined range. Therefore, a formed circuit is not limited by the input common mode voltage range of the amplifying portion. Also, the offset component can be minimized, while the output signal of the amplifying portion can be quickly converged to the vicinity of the reference potential.
According to a forty-first mode of the invention, in the micro signal processing circuit of the fortieth mode, the calculator, the low pass filter portion and the amplifying portion are constituted by a single common operational amplifier. According to the invention of the forty-first mode, since the calculator, the low pass filter portion and the amplifying portion are constituted of the common operational amplifier, the number of components can be reduced. A formed circuit is advantageous in mounting.
A forty-second mode of the invention provides a vibration detecting circuit which includes a vibration detector for detecting a vibration and emitting a vibration detecting signal, a low pass filter portion having an inverting input terminal for receiving the vibration detecting signal and a non-inverting input terminal with a reference potential applied thereto for removing a high-frequency component from the vibration detecting signal and an amplifying portion for receiving an output signal of the low pass filter portion. The invention of the forty-second mode includes the vibration detector for detecting the vibration and emitting the vibration detecting signal, the low pass filter portion having the inverting input terminal for receiving the vibration detecting signal and the non-inverting input terminal with the reference potential applied thereto for removing the high-frequency component from the vibration detecting signal and the amplifying portion for receiving the output signal of the low pass filter portion. Therefore, a formed circuit is not limited by the input common mode voltage range of the amplifying portion.
A forty-third mode of the invention provides a vibration detecting circuit which includes a vibration detector for detecting a vibration and emitting a vibration detecting signal, an amplifying portion having an inverting input terminal for receiving the vibration detecting signal and a non-inverting input terminal with a reference potential applied thereto and a low pass filter portion for receiving an output signal of the amplifying portion and removing a high-frequency component from the vibration detecting signal. The invention of the forty-third mode includes the vibration detector for detecting the vibration and emitting the vibration detecting signal, the amplifying portion having the inverting input terminal for receiving the vibration detecting signal and the non-inverting input terminal with the reference potential applied thereto and the low pass filter portion for receiving the output signal of the amplifying portion and removing the high-frequency component from the vibration detecting signal. Therefore, a formed circuit is not limited by the input common mode voltage range of the amplifying portion.
A forty-fourth mode of the invention provides a vibration detecting circuit which includes a vibration detector for detecting a vibration and emitting a vibration detecting signal, an output signal generator for generating an output signal, a calculator having an inverting input terminal for receiving the vibration detecting signal and a non-inverting input terminal with a reference potential applied thereto for performing a predetermined operation based on the vibration detecting signal and the output signal of the output signal generator, a low pass filter portion for removing a high-frequency component from an output signal of the calculator, an amplifying portion for receiving an output signal of the low pass filter portion and an operation signal generator for generating an operation signal when an output signal of the amplifying portion is not in a predetermined range. Based on the vibration detecting signal and the output signal of the output signal generator, the output signal of the amplifying portion is adjusted in the predetermined range. According to the invention of the forty-fourth mode, the calculator has the inverting input terminal to which the vibration detecting signal is transmitted and the non-inverting input terminal to which the reference potential is applied, and performs the predetermined operation based on the vibration detecting signal and the output signal of the output signal generator. The low pass filter portion removes the high-frequency component from the output signal of the calculator. The output signal of the low pass filter portion is transmitted to the amplifying portion. The operation signal generator generates the operation signal when the output signal of the amplifying portion is not in the predetermined range. Based on the vibration detecting signal and the output signal of the output signal generator, the output signal of the amplifying portion is adjusted in the predetermined range. Therefore, a formed circuit is not limited by the input common mode voltage range of the amplifying portion. Also, the offset component can be minimized, while the output signal of the amplifying portion can be quickly converged to the vicinity of the reference potential.
According to a forty-fifth mode of the invention, in the vibration detecting circuit of the forty-fourth mode, the calculator, the low pass filter portion and the amplifying portion are constituted by a single common operational amplifier. According to the invention of the forty-fifth mode, since the calculator, the low pass filter portion and the amplifying portion are constituted of the common operational amplifier, the number of components can be reduced. A formed circuit is advantageous in mounting.
According to a forty-sixth mode of the invention, in the vibration detecting circuit of the forty-fifth mode, when the vibration is decomposed to n axial components, n units of the vibration detectors are provided for detecting the vibrations along respective axial directions, and the operational amplifier is provided for each axis corresponding to the vibration detector. According to the invention of the forty-sixth mode, when the vibration is decomposed to n axial components, to detect the vibration along each axial direction, n units of the vibration detectors are provided, and corresponding to the vibration detectors the operational amplifier is provided for each axis. Therefore, the number of the operational amplifiers can be reduced, and a mounting space can be secured.